This invention relates to a catheter adapted to be inserted into a blood vessel and, more particularly, to a catheter suitably employed for treatment of heart diseases.
As the conventional medical treatment for ischemic heart diseases such as angina pectoris and myocardial infarctions, the so-called Percutaneous Transluminal Coronary Angioplasty method (abbreviated as "PTCA method" hereinafter) has been known. According to the PTCA method, and as shown in FIGS. 9(a)-(d),a catheter tube 4 having at the distal end an elongated balloon 3 made of polyurethane or the like is inserted into the stenosis 2 formed by a thrombus and cholesterol in the coronary 1, and the balloon is then positioned within the stenosis and expanded radially outwardly to expand the stenosis.
In this method, the location of the stenosis is first detrmined on the basis of a defective area of the shadow image given by an angiography and the balloon is then positioned and expanded.
However, in the above-mentioned PTCA method, since the conditions and nature of the stenosis is judged only from the unclear shadow image of the angiography, the method cannot pinpoint the exact conditions and nature of the stenosis and frequently fails to perform effective treatment. That is, in spite of the fact that other methods such as laser irradiation or injection of thrombus dissolving agent for treatment which depend upon the conditions and nature of the stenosis are appropriate, there are the cases in which effective treatment can not be performed because of the use of the PTCA method. Also, determination made only by means of a shadow image frequently fails to elicit any affirmative confirmation as to whether the balloon is properly positioned with respect to the constriction. Thus, it is said that the probability of the stenosis blocking up again after treatment by the conventional PTCA method is as high as 25-30%. SUMMARY OF THE INVENTION:
It is therefore a primary object of the present invention to provide a catheter which can pinpoint exactly the conditions and nature of the stenosis to be treated.
According to the present invention, a catheter adapted to be inserted into a blood vessel comprises a flexible tube-like sheath including a fluid passage therein and a radially expansive and contractive balloon disposed about the peripheral surface of the leading end portion of said sheath and communicating with said fluid passage is proposed. A light guide for transmitting illumination light to the distal end of said catheter, an image guide such as an image fiber bundle for transmitting an image from the distal end of said catheter, and a transparent liquid guide passage opening at the distal en of said catheter are disposed substantially parallel to each other within said flexible tube-like sheath, the catheter thereby including the concurrent function of an endoscope.
With the above-mentioned construction and arrangement of the components of the catheter according to the present invention, first of all, the catheter is inserted into a blood vessel while observation is made of a shadow image given by an angiography until the distal end of the catheter is positioned immediately short of the stenosis in the blood vessel. Transparent liquid is then spouted through the flush openings at the distal end of the catheter, and the conditions and nature of the stenosis are observed through the image fiber bundle, the balloon is expanded radially outward to expand the stenosis. After the catheter has been pulled out of the stenosis, it can be confirmed whether the stenosis has been properly expanded or not by observation through the image fiber bundle.